Select one or any combination of all four sets by tapping on the
set place and then tap "Start".

When tapping on the correct answer, the button will turn Green. If
the answer is incorrect the button will become Red, and the correct answer
will be shown by turning it to Green.

To see the performance results tap on "Results" icon on the main screen.

The leftmost button on the main screen shows which clef notes will be included in the cards. The default value is "Grand", which includes cards from Treble and Bass clefs. You can tap on that button and choose either from Grand (includes both Treble and Bass), Treble clef notes only, Bass clef notes only or Alto clef notes.